Hahaha, I swear everytime Tsushi posts before me, I just need to point and go: Yeah that!
What they understand:
Lupin: I definitely feel like Lupin knows a TON. He seems like he would totally be a polyglot, and would at least understand enough in context if nothing else. If I recall correctly he seemed to understand the obscure language Leticia knew in The First. (Was that Arcadian?)
Jigen: As for Jigen, I think he definitely has picked up a lot of chunks of languages from his travels/mercenary days with his father (Lupin Zero) and the merc alongside the military days that he speaks of a lot. Like Tsushi said, he seems to have been around Central and South America as well as the Middle East, and given what we've heard/seen, you could probably pick any country and could believe he may have been there at one point in time, either in the past or with Lupin. I don't think he has the same fluency and power to pick up any language like Lupin and many of his proficiencies may lie with basics / military / relevant termonology. I also think he understands a lot more than he can fluently speak. If for nothing else, than because Lupin is constantly bombarding him with it.
Goemon: He probably understands more than he seems to, as it's clear that Goemon is actually rather skilled and intelligent beyond what he often displays. But I imagine he's stubborn enough to make the others explain to him, doggedly just plows through anyway, or does his best to keep things to what he's most comfortable with (specifically Japanese)
Fujiko: She's probably similar to Lupin in many ways. I'm not sure she'd be quite as obsessed a polyglot at him and probably would prefer to limit herself to areas she frequents or, considering she's often with the rich and influential, she probably can get away with English a lot. It seems to be the current world "trade language" so plenty of the people she toys with probably can speak it. I imagine, she can understand more than she can speak and sometimes fakes being bad at a language / only being able to speak English or Japanese to help her play the "delicate, innocent, and dumb girl" that she uses to her advantage.
Zenigata: Somthing between Fujiko and Lupin. He focuses on what he's seen/heard Lupin speak and where he frequents the most. He struggles with fluency in a lot of places, but can carry on simple conversations, especially in his area of expertise, and if he's working with local officials, etc he can either use English "trade language arguement again" or might have an interpretor at least at workplaces. He understands more than he can say, though when it comes to Lupin, he can read his body language just as easily to understand a lot.
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What they prefer to / typically speak on a daily basis:
Lupin: I cannot possibly see Lupin NOT launching between tons of different languages, especially if he's really excited. Being in this man's brain must be maddening and is definitely NOT recommended by 4/5 doctors, and should be left to only him. He probably speaks Japanese, English, and French the most, but don't be surprised if he starts mixing in random exotic / dead languages because he's a little shit like that. He also knows swear words, crude words, and romance words in just about every language.
Jigen: He prefers and switches fluently between Japanese and English. He speaks French enough because it tends to slip out when he's talking with Lupin and Lupin is using it a lot. However, if he's in a place where he speaks the language, especially with shopkeepers, general populace, old buddies, contacts, he likely speaks the native tongue both out of respect, and to help curb him seeming as someone who might be taken advantage of. (Unless he's specifically trying to give off that vibe to suss something out)
Goemon: He prefers Japanese. He finds English clunky on his tongue but it's probably the second most common language he uses. He knows a lot more and CAN speak some of them decently, but unless he perceive it as being unduly rude, he probably just lets Lupin or Jigen do the talking.
Fujiko: She probably uses English the most often, Japanese being the second most often, especially around the group. She knows others and might use it in certain situations (perhaps French or Spanish while at a romantic dinner with Lupin, or other languages in general to show Lupin she's just as flexible as he is) but she probably keeps most of it discreet to help her fool others.
Zenigata: He prefers Japanese and probably ends up speaking English a lot (see "universal trade language argument and him traveling among ICPO jurisdiction that probably often uses it) but he can definitely speak decently, if not terribly eloquently, in the places he frequents most often.
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It must be a totaly mindbending blast to listen in to these guys at any point in time. I like to think that walking up on them, you'd likely heard Lupin and Jigen switching fluently between languages: Lupin because he can, it's relevent, it helps him convey his feelings/meaning better (some languages have unique descriptives/concepts/etc), and Jigen largely parrots back at him. Goemon mostly only speaks in Japanese, though he largely understands both Jigen and Lupin for the most part, though Jigen often replies to him in Japanese. Lupin is a wild card and not to be trusted. Fujiko likely speaks Japanese and English while around the team unless she's conversing specifically with Lupin and he's using another language/the local language. Zenigata probably largely uses Japanese around them.
There was an amazing video that I thought was on Youtube or Twitter, where someone spliced multiple language dubs from a scene in Castle of Cagliostro, showing Lupin, Jigen, and Goemon switching fluently with each other while carrying on a normal conversation. I can't seem to find it atm, though if anyone knows where this is, definitely let me know!
